Non-Christian sources that are used to study and establish the historicity of Jesus include Jewish sources such as Josephus, and Roman sources such as Tacitus. These sources are compared to Christian sources such as the Pauline Epistles and the Synoptic Gospels. These sources are usually independent of each other (i.e., Jewish sources do not draw upon Roman sources), and similarities and differences between them are used in the authentication process.[10][11]
Some scholars estimate that there are about 30 surviving independent sources written by 25 authors who attest to Jesus.[12]
^Dunn, James D. G. (2003). Jesus Remembered. Wm. B. Eerdmans. p. 339. ISBN978-0-8028-3931-2. States that baptism and crucifixion are "two facts in the life of Jesus command almost universal assent".
^Herzog, William R. (1998). Prophet and Teacher: An Introduction to the Historical Jesus. Westminster John Knox Press. pp. 1–6. ISBN978-0664225285.
^Crossan, John Dominic (1995). Jesus: A Revolutionary Biography. HarperOne. p. 145. ISBN978-0-06-061662-5. That he was crucified is as sure as anything historical can ever be, since both Josephus and Tacitus...agree with the Christian accounts on at least that basic fact.
^Evans, Craig A. (2001). Jesus and His Contemporaries: Comparative Studies. BRILL. pp. 2–5. ISBN978-0391041189.
^Chilton, Bruce; Evans, Craig A. (1998). Studying the Historical Jesus: Evaluations of the State of Current Research. BRILL. pp. 460–470. ISBN978-9004111424.